1. Field of the Disclosure
Embodiments of the present disclosure relate to a rotational angle detecting device using a potentiometer, and more particularly relate to a rotational angle detecting device which can prevent false detection.
2. Description of the Related Art
Conventionally, a rotational angle detecting device uses a potentiometer having two wipers at different wiping positions, as a rotational angle sensor, to detect rotational angle of a rotating shaft from change in potential output from the two wipers.
In a case of using a potentiometer as a rotational angle sensor, dead bands are formed near the ends of a resistor, and in a case where one wiper is situated at a boundary between the resistor and dead band, slight contact between the wiper and the resistor may result in false detection due to output of intermediate potential between the greatest potential and smallest potential as the output potential, in the same way as with the other wiper.
FIG. 6 illustrates a conventional example described in Japanese Unexamined Patent Application Publication No. 63-186102. A steering angle detecting device (rotational angle detecting device) 900 includes a shaft member 901, a supporting member 902, a resistor 903, first and second collectors 903a and 903b disposed on the resistor 903, steering angle calculating means 904, and steering angle correction computing means 905. A technique is disclosed where the steering angle calculating means 904 and steering angle correction computing means 905 detect and correct an angle from detection signals from the first collector 903a and second collector 903b, from the last time of sampling and this time of sampling.
However, the above-described conventional example has a problem in that false detection of angle may occur in a case where a collector (wiper) stays in slight contact and continues to output intermediate potential, since the angle is detected and corrected based on detection signals from the last time of sampling and this time of sampling.
These and other drawbacks exist.